1. Field of Invention
The present invention relates to the manufacture of hollow plastic bodies by extrusion blow molding, by extruding a blank in a mold cavity then blowing a gas into this blank to shape it to the walls of said cavity.
2. Description of Related Art
It is known that, to produce a curved tube by extrusion blow molding, one can create an air stream to blow the blank into the mold cavity simultaneously with extrusion.
However, this known process is not applicable to manufacture of a bundle of at least two curved, joined tubes because the blank must be clamped in the mold cavity along at least one line parallel to the generatrices of the bundle to produce air tightness between the tubes upon blowing, and such clamping resists displacement of the blank in the mold cavity under the influence of the entraining air stream.